Question: Express this number in scientific notation. $\text{31 billion}$
Solution: $\text{31 billion}$ can be written as $31{,}000{,}000{,}000$ in standard form. There are ${10}$ digits to the right of the leading ${3}$ (and to the left of the decimal). So: $\text{31 billion} = {3.1} \times 10^{{10}}$